"Weightless" proxy atoms on the ISS unlock the mysteries of smart fluids

February 25, 2020

WACO, Texas (February 25, 2020) From advanced shock absorbers in automobiles to soft robotic components, and even artificial heart valves, smart fluids are revolutionizing many aspects of modern-day life. Smart fluids have the unique ability to change their mechanical properties when acted upon by electric or magnetic fields. However, the exact mechanisms allowing the atoms and molecules in these fluids to ‘react’ to small changes in the surrounding environment is still unknown.

To tackle this mystery, scientists from CASPER have designed experiments carried out on the International Space Station (ISS) where tiny plastic spheres are charged in a plasma environment and act like proxy atoms, self-organizing into complex fluids. The CASPER team studies the fundamental principles of order and stability in these dust-plasma structures, using video cameras to capture how the charged spheres respond to changes in the plasma environment. To eliminate the effect of gravity, which normally would cause the dust to settle out of the center of the plasma environment, the experiments were performed in the Plasma Kristall-4 (PK-4) device on board the ISS. After the experiments were carried out in July as part of PK-4 ISS Campaign 7, the data was flown back to earth and CASPER scientists have recently been able to review the results of their experiment. The experiments are designed to investigate how dusty plasma fluids change their structure from homogeneous (or smooth) to filamentary (made of strings of particles) when acted upon by electric fields. The analysis of data from these experiments is expected to unlock a variety of new applications for electrorheological fluids on Earth, whose atoms are known to undergo homogeneous-to-string transitions similar to those observed in dusty plasmas in space.

Lori Scott (BS "16), a graduate student at Auburn University, directs the experiments from Mission Control in Toulouse, France. She is currently there to oversee the second experiment which will be run on Thursday, February 27. She reports, “Being in mission control for our experiment and talking with the cosmonauts is an amazing experience! It was incredible to see the livestream of them running and interacting with the experiment while floating around in the Columbus module. They are the eyes for our experiment, capturing the dust particles [in the camera field of view] without the time delay that would exist if we had to send all instructions from the ground. It was so rewarding to be in Mission Control and see our two-year development process come together successfully for Campaign 7. I am excited to be here again for Campaign 9!”

About PK-4: Plasma Kristall is the first natural science experiment performed on the ISS and the longest-running series of experiments in the history of human spaceflight. PK-4 (the fourth generation of Plasma Kristall) is the first experiment of that series with direct involvement of US research teams, including the CASPER group. US involvement with PK-4 was funded by a NSF/NASA collaboration.

About CASPER: CASPER consists of seven independent groups that conduct theoretical, numerical, and experimental in work in various research fields, ranging from plasma physics to space engineering, to cosmology and early universe. Members of the center are also involved with educational research and outreach activities.

About ISS: The ISS is the largest human-made object in lower orbit around the Earth. It has been continuously inhabited by humans for the past 22 years. Life and science on the ISS pave the way for establishing a permanent human presence on the surface of the Moon and Mars.

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